The invention relates to a camera useful in a stereophotogrammetric assembly which is, in turn, useful for ultimate close range stereometric measurements of objects such as, for example, of human body forms. Stereometric measurement of body forms from substantially simultaneously recorded front and rear view stereopairs has recently been developed as an effective technique for determining body and limb volume changes and related phenomena for a wide variety of purposes. In this arrangement, a three-dimensional optical model is created from the stereo photo images, which model may be displayed and measured in stereoplotting instruments. The measurements of body geometry which are read off the stereo model can be stored electrically, magnetically, or via other media in graphical or digital form. Reports detailing studies of body geometry by employing stereophotogrammetry in general include "Stereometric Measurement of Body and Limb Volume Changes During Extended Space Missions", Texas Institute for Rehabilitation and Research, Report No. NAS 9-10567 dated March, 1971, and "Experimental Determination of Mechanical Features of Children and Adults", Texas Institute for Rehabilitation and Research, Report No. DOT-HS-231-2-397, dated February, 1974, the disclosures of which are hereby incorporated by reference in the present specification.
In utilizing stereophotogrammetric equipment for quantitative measurement of relatively small close range objects such as the human body it is necessary that precision and accuracy be of foremost importance. The film utilized must be of high resolution so as to register fine lines of distinction, and must be held substantially perfectly flat during exposure thereof in order to obtain quantitatively accurate pictorial representations for stereoplotting. The focusing distance of the camera lenses must be finely adjustable, and the lenses must be positively guided. In order to provide for accuracy in matching up and interpreting the various pictures that are taken to produce a three-dimensional model, fiducial marks and a lens reference should be provided on the pictures themselves. Also, since film of sufficient quality for stereophotogrammetry is expensive, wastage thereof should be minimized.
The camera according to the present invention achieves all the above goals, providing a camera that produces accurate, fiducially referenced pictures with minimum film wastage. The assembly according to the present invention also provides for easy loading and unloading of film with readily releasable positive flat clamping thereof during exposure. Fiducial flash units according to the present invention are self contained within the camera eliminating the need for excessive light piping and the like.
According to the present invention, a stereometric camera is provided for use in an exemplary assembly having a pair of camera supports each having a pair of horizontal guide rails with a middle flash lamp assembly and right and left hand cameras associated therewith. One camera assembly takes a front view of the subject, and the other takes a rear view of the subject. Each camera includes a housing releasably attached to a film housing, the film housing having a handle thereon for ready handling thereof if detached from the camera housing. A lens and solenoid operated shutter assembly are associated with each camera, being mounted in a lens housing which is reciprocally adjustable with respect to the camera housing. Fine adjustment means for the lens housing are provided, and lens reciprocation is positively guided.
A flat glass plate associated with the camera housing is provided for supporting the film. It is necessary that means be provided for holding the film perfectly flat against the glass plate during exposure, and according to the present invention this is provided by a film holding plate-like member of sponge rubber or the like operatively connected to a shaft. In order to provide for ease of movement of the film holder while still providing a tight hold therewith, an overcenter toggle arrangement is provided. The toggle arrangement includes a trigger pivotally mounted to the shaft and to a lever mounted to the film housing, the trigger having a portion thereof adapted to be grasped by the operator's hand. A spring provides a biasing force for normally biasing the holding member into holding position, and the shaft is reciprocally guided by a housing bushing and a bushing through the film housing handle.
Film may be brought into operative relationship with the flat glass plate by a film magazine that is releasably attachable to the film housing. The magazine may comprise a hollow plate-like member having a piece of polyester based film 4-7 mills thick, or the like, disposed therein. A control piece extends from one end of the magazine, and by reciprocation thereof one is able to move the film in and out of the open end of the magazine opposite the control piece. The magazine is releasably connected to the film housing by a pivot and by cooperating latching projections and plates on the magazine and film housing respectively. A continuous controllably advanced film roll can be utilized in place of the magazine.
A fiducial marking assembly is provided for photographically marking the film with accurate fiducial marks during exposure thereof. The fiducial assembly comprises four orifices extending through the glass plate, one located at either side of the film held against the glass plate at the vertical midpoint thereof, and one located on top and one on the bottom of the film being held at opposite points spaced from the horizontal midpoint of the film. Light piping extends from each of these orifices to an internal flash unit which is synchronized with the flash lamp assembly, and a dial indicator driven by lens adjustments to indicate the instantaneous actual focusing distance of the lens is also in the path of the internal flash so that it is registered on the film too in a corner thereof. The lens is also located off horizontal center of the camera housing, toward the strobe assembly, the center of the lens when projected onto the glass plate providing the intersection point of lines extending from one horizontal fiducial orifice to the other and from one vertical fiducial orifice to the other. This arrangement allows for orientation of the film so that there is no wastage thereof in photographing empty space to one side of the subject.
It is the primary object of the present invention to provide improved stereophotogrammetric camera equipment. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.